Conductive film, display device equipped with same, and method for determining pattern of conductive film

ABSTRACT

This conductive film has a randomized wiring pattern having randomized rhomboid shapes obtained by giving irregularity in a predetermined range to rhomboid shapes of a rhomboidal wiring pattern which, with respect to frequencies of moire and intensities of moire obtained by applying a visual response characteristic of human beings to frequency information of moire and intensity information of moire calculated from peak frequencies and peak intensities in both two-dimensional Fourier spectra of transmittance image data of the wiring pattern and transmittance image data of the pixel array pattern, causes a sum of intensities of moire each corresponding to each of frequencies of moire falling within a predetermined frequency range determined depending on the visual response characteristic to be less than or equal to a predetermined value. The conductive film allows suppression of moire and significant improvement in visibility.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/JP2013/055287 filed on Feb. 28, 2013, which claims priority under 35U.S.C. §119(a) to Japanese Patent Application No. 2012-082706 filed onMar. 30, 2012. Each of the above applications is hereby expresslyincorporated by reference, in its entirety, into the presentapplication.

BACKGROUND OF THE INVENTION

The present invention relates to a conductive film, a display deviceequipped with the conductive film, and a method for determining apattern of the conductive film.

Examples of a conductive film installed on a display unit of a displaydevice (hereinafter also referred to as “display”) include a conductivefilm for electromagnetic shields and a conductive film for touch panels(for example, see JP 2009-117683 A and JP 2011-216379 A).

JP 2009-117683 A, a published patent application filed by the sameapplicant as the present application, discloses that a second pattern,which is generated from second pattern data in which the relativedistance between spectrum peaks of two-dimensional Fourier spectrums(2DFFT Sp) of the respective pattern data of a first pattern such as apixel array pattern (for example, a black matrix (hereinafter alsoreferred to as “BM”) pattern) of a display and the second pattern suchas an electromagnetic shield pattern is greater than a predeterminedspatial frequency, for example, 8 cm⁻¹, is automatically selected.

JP 2009-117683 A also discloses that when the relative distance is notgreater than the predetermined spatial frequency, changing of one ormore of a rotation angle, a pitch and a pattern width in the secondpattern data to generate new second pattern data is repeated until therelative distance is greater than the predetermined spatial frequency.

In this way, in JP 2009-117683 A, it is possible to automatically selectan electromagnetic shield pattern that can suppress the occurrence ofmoire and that can avoid an increase in surface resistivity ordegradation in transparency.

JP 2011-216379 A, another published patent application filed by the sameapplicant as the present application, discloses a transparent conductivefilm having a mesh pattern comprising a plurality of polygonal meshes,in which the mesh pattern is formed such that, in relation to a centroidspectrum of respective meshes, an average intensity on the side of aspatial frequency band higher than a predetermined spatial frequency,for example, a spatial frequency at which a human visual responsecharacteristic corresponds to 5% of the maximum response, is greaterthan an average intensity on the side of a spatial frequency band lowerthan the predetermined spatial frequency.

It is stated in JP 2011-216379 A that a transparent conductive film isprovided which is capable of lowering the sensation of granular noisecaused by the pattern and significantly enhancing the visibility ofobjects to be observed, and has a stable power capability even afterbeing cut.

SUMMARY OF THE INVENTION

In the technology as disclosed in JP 2009-117683 A, during thegeneration of a wiring pattern of a conductive film, a moire frequencyis only controlled on the basis of frequency information of a BM (blackmatrix) pattern of a display/the wiring pattern so as to provide awiring pattern excellent in visibility, that is to say, thedetermination of whether moire is visually recognized or not onlydepends on the frequency. Since human perception of moire is influencedby intensity as well as frequency, moire may be visually recognizeddepending on the intensity even at a frequency at which moire is notdetermined to be visually recognized in JP 2009-117683 A, and thus thereis a problem in that the wiring pattern of the conductive film is notadequately improved in visibility of moire. Particularly when thetechnology of JP 2009-117683 A is applied to a conductive film for touchpanels, since the conductive film is pressed with a finger or the like,a delicate distortion occurs between the BM/wiring patterns, andaccordingly there is a problem in that visual recognition of moire dueto intensity is promoted, leading to an inadequate improvement in moirevisibility.

In JP 2011-216379 A, in relation to a centroid spectrum of respectivemeshes of the mesh pattern of the transparent conductive film, anaverage intensity in a mid to high spatial frequency band, which ishigher than the predetermined spatial frequency and in which humanvisual response characteristic rapidly decreases, is made greater thanan average intensity in a low spatial frequency band, in which humanvisual response characteristic is high, so as to reduce the sensation ofnoise visually perceived by human beings. The disclosed invention merelyaims at reducing the sensation of noise of the mesh pattern in itself ofthe transparent conductive film and is not drawn to the improvement inmoire visibility by suppressing moire occurring between the BM patternof the display and the mesh pattern of the transparent conductive film.

The present invention has been made in order to solve theabove-described problems with the prior art, and an object of thepresent invention is to provide a conductive film capable of suppressingthe occurrence of moire to greatly improve visibility, a display deviceequipped with such a conductive film, and a method for determining apattern of a conductive film.

In particular, the present invention aims at providing a conductive filmwhich is capable of suppressing the occurrence of moire considerablydeteriorating the image quality when a transparent conductive film withwiring is used as an electrode of a touch panel and a display unit of adisplay device is viewed through the conductive film superimposed on ablack matrix of the display unit, so as to greatly improve visibility ofthe display on the touch panel, a display device equipped with such aconductive film, and a method for determining a pattern of a conductivefilm.

In order to achieve the objects as above, the conductive film accordingto a first aspect of the present invention is a conductive film adaptedto be installed on a display unit of a display device, comprising: atransparent substrate; and a conductive portion including a plurality ofthin metal wires that is formed on at least one surface of thetransparent substrate, wherein the conductive portion has a wiringpattern obtained by giving irregularity to a rhomboidal wiring pattern,the wiring pattern being formed by the plurality of thin metal wires ina meshed manner and arraying a plurality of openings, wherein the wiringpattern is superimposed on a pixel array pattern of the display unit,and wherein the wiring pattern is a randomized wiring pattern havingrandomized rhomboid shapes obtained by giving the irregularity in apredetermined range determined depending on a width of the thin metalwires to rhomboid shapes of the rhomboidal wiring pattern which, withrespect to frequencies of moire and intensities of moire obtained byapplying a visual response characteristic of human beings to frequencyinformation of moire and intensity information of moire calculated frompeak frequencies and peak intensities of plural spectrum peaks in atwo-dimensional Fourier spectrum of transmittance image data of therhomboidal wiring pattern and peak frequencies and peak intensities ofplural spectrum peaks in a two-dimensional Fourier spectrum oftransmittance image data of the pixel array pattern, causes a sum ofintensities of moire each corresponding to each of frequencies of moirefalling within a predetermined frequency range determined depending onthe visual response characteristic to be less than or equal to apredetermined value.

In order to achieve the objects as above, the display device accordingto a second aspect of the present invention is a display devicecomprising: a display unit; and the conductive film according to thefirst aspect that is installed on the display unit.

In order to achieve the objects as above, the method for determining awiring pattern of a conductive film according to a third aspect of thepresent invention is a method for determining a wiring pattern of aconductive film, with the conductive film being adapted to be installedon a display unit of a display device and to have a wiring patternobtained by giving irregularity to a rhomboidal wiring pattern, saidwiring pattern being formed by the plurality of thin metal wires in ameshed manner and arraying a plurality of openings, comprising the stepsof: acquiring transmittance image data of a predetermined wiring patternand transmittance image data of a pixel array pattern of the displayunit, on which pattern the predetermined wiring pattern is superimposed;calculating peak frequencies and peak intensities of plural spectrumpeaks in a two-dimensional Fourier spectrum of the transmittance imagedata of the predetermined wiring pattern and peak frequencies and peakintensities of plural spectrum peaks in a two-dimensional Fourierspectrum of the transmittance image data of the pixel array pattern byperforming a two-dimensional Fourier transform on the transmittanceimage data of the predetermined wiring pattern and the transmittanceimage data of the pixel array pattern; calculating frequency informationof moire and intensity information of moire from the peak frequenciesand the peak intensities of the predetermined wiring pattern and thepixel array pattern thus calculated, respectively; calculatingfrequencies of moire and intensities of moire by applying a visualresponse characteristic of human beings to the frequency information ofmoire and the intensity information of moire thus obtained; makingcomparison with respect to the frequencies of moire and the intensitiesof moire thus obtained such that a sum of intensities of moire eachcorresponding to each of frequencies of moire falling within apredetermined frequency range determined depending on the visualresponse characteristic is compared with a predetermined value; changingthe transmittance image data of the predetermined wiring pattern totransmittance image data of a new wiring pattern if the sum of theintensities of moire is greater than the predetermined value, andrepeating the steps of calculating the peak frequencies and the peakintensities, calculating the frequency information of moire and theintensity information of moire, calculating the frequencies of moire andthe intensities of moire, and making comparison between the sum of theintensities of moire and the predetermined value until the sum of theintensities of moire is less than or equal to the predetermined value;setting a rhomboidal wiring pattern which causes the sum of theintensities of moire to be less than or equal to the predetermined valueas the wiring pattern of the conductive film; and giving theirregularity in a predetermined range determined depending on a width ofthe thin metal wires to rhomboid shapes of the set rhomboidal wiringpattern, and determining a randomized wiring pattern having randomizedrhomboid shapes that the irregularity is given to be the wiring patternof the conductive film.

In each of the first, second and third aspects, it is preferable that,when a direction in which the irregularity is given to the rhomboidshape is a direction parallel or perpendicular to a side of rhomboid,the irregularity is defined as a ratio of an average according to anormal distribution for a pitch of rhomboid after the irregularity isgiven with respect to the pitch of rhomboid before the irregularity isgiven, and that the predetermined range of the irregularity is from 2%to 20% when the width of the thin metal wires is less than or equal to 3μm and the predetermined range of the irregularity is from 2% to 10%when the width of the thin metal wires is greater than 3 μm.

The pitch of rhomboid is preferably preserved before and after theirregularity is given when the direction in which the irregularity isgiven to the rhomboid shape is the direction parallel to a side ofrhomboid, and an angle of rhomboid is preferably preserved before andafter the irregularity is given when the direction in which theirregularity is given to the rhomboid shape is the directionperpendicular to a side of rhomboid.

It is also preferable that the predetermined frequency range of thefrequency of moire is up to 3 cycles/mm, and that the wiring patternundergoes ranking for optimization if it involves a frequency of moireless than or equal to 3 cycles/mm, and the wiring pattern undergoing theranking for optimization causes the sum of intensities of moire to beless than or equal to 0 in terms of common logarithm on condition thatthe wiring pattern does not undergo the ranking for optimization if itinvolves an intensity of moire greater than or equal to −5 in terms ofcommon logarithm at a frequency of moire less than or equal to 1.8cycles/mm and if it involves an intensity of moire greater than or equalto −3.7 in terms of common logarithm at a frequency of moire greaterthan 1.8 cycles/mm but not greater than 3 cycles/mm.

Preferably, the frequency information of moire is given as differencesbetween the peak frequencies of the wiring pattern and the peakfrequencies of the pixel array pattern and the intensity information ofmoire is given as products of the peak intensities of the wiring patternand the peak intensities of the pixel array pattern.

The frequency of moire and the intensity of moire are preferablyobtained by performing convolution with a visual transfer function asthe visual response characteristic on the frequency information of moireand the intensity information of moire. The visual transfer function ispreferably a function in which attenuation in sensitivity tolow-frequency components is removed from a Dooley-Shaw function as abasis.

It is preferable that the peak intensities are each an average ofintensities in a plurality of pixels around the peak position, and arenormalized with the transmittance image data of the wiring pattern andthe pixel array pattern.

The pixel array pattern is preferably a black matrix pattern.

The frequency information of moire is preferably obtained as differencesbetween the peak frequencies of the wiring pattern and the peakfrequencies of the pixel array pattern, and the intensity information ofmoire is preferably obtained as products of two sets of vectorintensities, with one set comprising the peak intensities of the wiringpattern and the other comprising the peak intensities of the pixel arraypattern.

As described above, according to the present invention, it is possibleto suppress the occurrence of moire to greatly improve visibility.

That is, in the present invention, since the frequencies/intensities ofmoire are calculated from the peak frequencies/intensities obtained byfrequency analysis of the pixel array pattern of the display device andthe wiring pattern of the conductive film and the calculated intensitiesand frequencies of moire are numerically limited so as to obtainexcellent visibility and the irregularity is given to the wiringpattern, it is possible to prevent the deterioration of image qualitydue to the occurrence of moire and thus to achieve excellent visibility.

Particularly, according to the present invention, it is possible tosuppress moire considerably deteriorating the image quality when aconductive film is used as an electrode of a touch panel and a displayunit of a display device is viewed through the conductive filmsuperimposed on a black matrix of the display unit, so as to greatlyimprove visibility of the display on the touch panel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view schematically illustrating an example of aconductive film according to a first embodiment of the presentinvention.

FIG. 2 is a partial cross-sectional view schematically illustrating theconductive film illustrated in FIG. 1.

FIG. 3 is a partial cross-sectional view schematically illustrating anexample of a conductive film according to a second embodiment of thepresent invention.

FIG. 4 is a diagram schematically illustrating an example of a pixelarray pattern in a part of a display unit to which the conductive filmaccording to the present invention is applied.

FIG. 5 is a cross-sectional view schematically illustrating an exampleof a display device in which the conductive film illustrated in FIG. 3is incorporated.

FIG. 6 is a flowchart illustrating a part of an example of a method fordetermining a wiring pattern of a conductive film according to thepresent invention.

FIG. 7A is a diagram schematically illustrating an example of a pixelarray pattern of the display unit to which the conductive film accordingto the present invention is applied, FIG. 7B is a diagram schematicallyillustrating an example of a wiring pattern of the conductive filmsuperimposed on the pixel array pattern illustrated in FIG. 7A, and FIG.7C is a partially enlarged view of the pixel array pattern illustratedin FIG. 7A.

FIG. 8 is a diagram schematically illustrating an example of flippingprocessing that is performed in preparing transmission image data in themethod for determining a wiring pattern illustrated in FIG. 6.

FIGS. 9A and 9B are diagrams respectively illustrating intensitycharacteristics of two-dimensional Fourier spectrums of transmittanceimage data of the pixel array pattern illustrated in FIG. 7A and thewiring pattern illustrated in FIG. 7B.

FIG. 10 is a graph illustrating frequency peak positions of the pixelarray pattern of the display unit illustrated in FIG. 7A.

FIGS. 11A and 11B are graphs illustrating an example of the intensitycharacteristic of a two-dimensional Fourier spectrum with a curve andbars, respectively.

FIG. 12 is a diagram schematically illustrating frequency informationand intensity information of moire generated by interference of thepixel array pattern illustrated in FIG. 7A and the wiring patternillustrated in FIG. 7B.

FIG. 13 is a graph illustrating an example of a standard visual responsecharacteristic of human beings.

FIG. 14 is a diagram schematically illustrating an example of anoptimized wiring pattern determined using the method for determining awiring pattern illustrated in FIG. 6.

FIGS. 15A, 15B, and 15C are diagrams illustrating wiring patterns ofexamples and a comparative example, respectively.

FIGS. 16A, 16B, and 16C are diagrams illustrating wiring patterns of theexamples and the comparative example, respectively.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, a conductive film and a method for determining a pattern ofa conductive film according to the present invention will be describedin detail with reference to appropriate embodiments illustrated in theaccompanying drawings.

In the following description, a conductive film for a touch panel willbe explained as a representative example of the conductive filmaccording to the present invention, although the present invention isnot limited to this example. The conductive film of the invention may beof any type as long as it is a conductive film installed on a displayunit of a display device such as a liquid crystal display (LCD), aplasma display panel (PDP), an organic electroluminescence display(OLED), or an inorganic EL display. It is needless to say that theconductive film according to the present invention may be, for example,a conductive film for electromagnetic shields.

FIGS. 1 and 2 are respectively a plan view schematically illustrating anexample of a conductive film according to a first embodiment of thepresent invention and a schematic partial cross-sectional view thereof.

A conductive film 10 according to this embodiment illustrated in thedrawings is to be installed on a display unit of a display device and isa conductive film having a wiring pattern that is excellent insuppression of occurrence of moire with respect to a black matrix (BM)of the display unit, particularly, a wiring pattern that is optimized interms of visibility of moire with respect to the BM pattern when it issuperimposed on the BM pattern. The conductive film 10 includes atransparent substrate 12, a conductive portion 16 that is formed on onesurface of the transparent substrate 12 (surface on the upper side inFIG. 2) and that is composed of plural thin wires made of metal(hereinafter referred to as “thin metal wires”) 14, and a protectivelayer 20 bonded to the substantially entire surface of the conductiveportion 16 via an adhesive layer 18 so as to cover the thin metal wires14.

The transparent substrate 12 is formed of a material having aninsulating property and having a high light-permeability, and examplesthereof include a resin, glass, and silicon. Examples of the resininclude polyethylene terephthalate (PET), polymethyl methacrylate(PMMA), polypropylene (PP), and polystyrene (PS).

The conductive portion 16 has a wiring pattern 24 of a meshed shapewhich is formed by the thin metal wires 14 with openings 22 betweenneighboring thin metal wires 14. The thin metal wires 14 are notparticularly limited as long as they are made of metal having highconductivity, with an example being those made of gold (Au), silver (Ag)or copper (Cu). While it is more preferable indeed in terms ofvisibility if the thin metal wires 14 have a smaller line width, theline width has only to be 30 μm or smaller, for instance. Forapplication to a touch panel, the line width of the thin metal wires 14preferably ranges from 0.1 μm to 15 μm, more preferably from 1 μm to 9μm, and still more preferably from 2 μm to 7 μm.

Specifically, the conductive portion 16 has the wiring pattern 24 inwhich the thin metal wires 14 are arranged in a meshed manner. In thepresent invention, the mesh shape of the openings 22 is a rhomboid-basedshape with predetermined irregularity given thereto. The presentinvention is not limited in mesh shape to the illustrated example, andany rhomboid-based shape may be employed as long as it has beenrandomized by giving predetermined irregularity to the rhomboidal wiringpattern as optimized in terms of visibility of moire with respect to apredetermined BM pattern to be described later. For example, shape intowhich the rhomboid shape is deformed such as a quadrangle including aparallelogram may be employed.

As a material of the adhesive layer 18, a wet lamination adhesive, a drylamination adhesive, a hot melt adhesive or the like can be mentioned.

Similarly to the transparent substrate 12, the protective layer 20 isformed of a material having a high light-permeability, such as a resin,glass, and silicon. The refractive index n1 of the protective layer 20is preferably of a value equal to or close to that of the refractiveindex n0 of the transparent substrate 12. In that case, the relativerefractive index nr1 of the transparent substrate 12 with respect to theprotective layer 20 is approximately 1.

In this specification, the refractive index refers to a refractive indexfor the light at a wavelength of 589.3 nm (sodium D ray). For example,in regard to resins, the refractive index is defined by ISO 14782: 1999(corresponding to JIS K 7105) that is an international standard. Inaddition, the relative refractive index nr1 of the transparent substrate12 with respect to the protective layer 20 is defined as nr1=n1/n0.Here, it is preferable that the relative refractive index nr1 be in arange of 0.86 to 1.15, and a range of 0.91 to 1.08 is more preferable.

By limiting the range of the relative refractive index nr1 as above tocontrol light transmittance between two members, the transparentsubstrate 12 and the protective layer 20, improvement in moirevisibility is further promoted.

The conductive film 10 according to the first embodiment described abovehas the conductive portion 16 on only one surface of the transparentsubstrate 12, but the present invention is not limited to thisconfiguration, and the conductive film 10 may have the conductiveportion on both surfaces of the transparent substrate 12.

FIG. 3 is a partial cross-sectional view schematically illustrating anexample of a conductive film according to a second embodiment of thepresent invention. The plan view of the conductive film according to thesecond embodiment illustrated in FIG. 3 is the same as the plan view ofthe conductive film according to the first embodiment illustrated inFIG. 1 and accordingly, will be omitted.

As illustrated in the drawing, a conductive film 11 according to thesecond embodiment includes a first conductive portion 16 a and a dummyelectrode portion 26 formed on one surface (on the upper side in FIG. 3)of a transparent substrate 12, a second conductive portion 16 b formedon the other surface (on the lower side in FIG. 3) of the transparentsubstrate 12, a first protective layer 20 a bonded to the substantiallyentire surface of the first conductive portion 16 a and the dummyelectrode portion 26 through a first adhesive layer 18 a, and a secondprotective layer 20 b boned to the substantially entire surface of thesecond conductive portion 16 b through a second adhesive layer 18 b.

In the conductive film 11, the first conductive portion 16 a and thedummy electrode portion 26 are each composed of plural thin metal wires14 and formed on one surface (on the upper side in FIG. 3) of thetransparent substrate 12, and the second conductive portion 16 b iscomposed of plural thin metal wires 14 and formed on the other surface(on the lower side in FIG. 3) of the transparent substrate 12. Here, thedummy electrode portion 26 is formed on one surface (on the upper sidein FIG. 3) of the transparent substrate 12 similarly to the firstconductive portion 16 a, and has the thin metal wires 14 similarlyarranged at positions corresponding to the thin metal wires 14 of thesecond conductive portion 16 b formed on the other surface (on the lowerside in FIG. 3), as illustrated in the drawing.

The dummy electrode portion 26 is separated from the first conductiveportion 16 a by a predetermined distance and is in the state of beingelectrically insulated from the first conductive portion 16 a.

In the conductive film 11 according to this embodiment, since the dummyelectrode portion 26 composed of plural thin metal wires 14corresponding to the plural thin metal wires 14 of the second conductiveportion 16 b formed on the other surface (on the lower side in FIG. 3)of the transparent substrate 12 is formed on one surface (on the upperside in FIG. 3) of the transparent substrate 12, scattering due to thethin metal wires on the one surface (on the upper side in FIG. 3) of thetransparent substrate 12 can be controlled, and it is thus possible toimprove visibility of electrode.

Here, the first conductive portion 16 a and the dummy electrode portion26 have a wiring pattern 24 of a meshed shape which is formed by thethin metal wires 14 and openings 22. The second conductive portion 16 bhas a wiring pattern 24 of a meshed shape which is formed by the thinmetal wires 14 and openings 22, similarly to the first conductiveportion 16 a. As described above, the transparent substrate 12 is formedof an insulating material and the second conductive portion 16 b is inthe state of being electrically insulated from the first conductiveportion 16 a and the dummy electrode portion 26.

In addition, the first and second conductive portions 16 a and 16 b andthe dummy electrode portion 26 can be similarly formed of the samematerial as the conductive portion 16 of the conductive film 10illustrated in FIG. 2.

The first protective layer 20 a is bonded to the substantially entiresurface of the first conductive portion 16 a and the dummy electrodeportion 26 with the first adhesive layer 18 a so as to cover the thinmetal wires 14 of the first conductive portion 16 a and the dummyelectrode portion 26.

The second protective layer 20 b is bonded to the substantially entiresurface of the second conductive portion 16 b with the second adhesivelayer 18 b so as to cover the thin metal wires 14 of the secondconductive portion 16 b.

Here, the first adhesive layer 18 a and the second adhesive layer 18 bcan be similarly formed of the same material as the adhesive layer 18 ofthe conductive film 10 illustrated in FIG. 2, and the material of thefirst adhesive layer 18 a may be the same as or different from thematerial of the second adhesive layer 18 b.

The first protective layer 20 a and the second protective layer 20 b canbe similarly formed of the same material as the protective layer 20 ofthe conductive film 10 illustrated in FIG. 2, and the material of thefirst protective layer 20 a may be the same as or different from thematerial of the second protective layer 20 b.

The refractive index n2 of the first protective layer 20 a and therefractive index n3 of the second protective layer 20 b are each of avalue equal or close to that of the refractive index n0 of thetransparent substrate 12, similarly to the protective layer 20 of theconductive film 10 according to the first embodiment. In that case, therelative refractive index nr2 of the transparent substrate 12 withrespect to the first protective layer 20 a and the relative refractiveindex nr3 of the transparent substrate 12 with respect to the secondprotective layer 20 b are each approximately 1. Here, the definitions ofthe refractive index and the relative refractive index are the same asthe definitions in the first embodiment. Accordingly, the relativerefractive index nr2 of the transparent substrate 12 with respect to thefirst protective layer 20 a is defined as nr2=n2/n0, and the relativerefractive index nr3 of the transparent substrate 12 with respect to thesecond protective layer 20 b is defined as nr3=n3/n0.

Here, similarly to the relative refractive index nr1, it is preferablethat the relative refractive index nr2 and the relative refractive indexnr3 be in a range of 0.86 to 1.15, and a range of 0.91 to 1.08 is morepreferable.

By limiting the range of the relative refractive index nr2 and therelative refractive index nr3 as above, improvement in moire visibilityis further promoted, as is the case with the limitation of the range ofthe relative refractive index nr1.

The conductive film 10 according to the first embodiment and theconductive film 11 according to the second embodiment of the presentinvention are applied to, for example, a touch panel of a display unit30 (displaying section), of which a part is schematically illustrated inFIG. 4, and as such each have the rhomboidal wiring pattern as optimizedin terms of visibility of moire with respect to the pixel array pattern,namely, black matrix (hereinafter also referred to as “BM”) pattern ofthe display unit 30 and then given irregularity (or, randomized). In thepresent invention, the rhomboidal wiring pattern as optimized in termsof visibility of moire with respect to the BM (pixel array) patternrefers to a rhomboidal wiring pattern or a group of two or morerhomboidal wiring patterns making moire with respect to a predeterminedBM pattern not perceived by human visual sensation. In the presentinvention, a group of two or more rhomboidal wiring patterns optimizedmay be ranked, from a rhomboidal wiring pattern making moire mostdifficult to perceive to a rhomboidal wiring pattern making moiresomewhat difficult to perceive, so as to determine one rhomboidal wiringpattern which makes moire most difficult to perceive.

Further, in the present invention, the wiring pattern as optimized interms of visibility of moire with respect to the BM (pixel array)pattern and then given irregularity (or, randomized) refers to a wiringpattern obtained by giving predetermined irregularity to the optimizedwiring pattern as above in a predetermined direction, such as directionsparallel and perpendicular to a side of the rhomboid of the wiringpattern, so as to randomize the optimized wiring pattern.

The optimization of a wiring pattern in terms of visibility of moirewith respect to a predetermined BM pattern and the giving ofirregularity to the optimized wiring pattern, which are essential to thepresent invention, will be described later.

The conductive film according to the present invention basically has theabove-mentioned configuration.

FIG. 4 is a diagram schematically illustrating an example of a pixelarray pattern in a part of the display unit to which the conductive filmaccording to the present invention is applied.

As partially illustrated in FIG. 4, the display unit 30 has pluralpixels 32 arrayed therein in a matrix shape to form a predeterminedpixel array pattern. Each pixel 32 has a configuration in which threesub-pixels (a red sub-pixel 32 r, a green sub-pixel 32 g, and a bluesub-pixel 32 b) are arranged in a horizontal direction. Each sub-pixelhas a rectangular shape which is long in a vertical direction. The arraypitch in the horizontal direction (horizontal pixel pitch Ph) of thepixels 32 and the array pitch in the vertical direction (vertical pixelpitch Pv) of the pixels 32 are substantially equal to each other. Thatis, a shape formed by one pixel 32 and a black matrix (BM) 34 (patternmaterial) surrounding the one pixel 32 is square (see a hatched area36). The aspect ratio of each pixel 32 is not equal to 1 but is so setas to satisfy the inequality: [the length in the horizontal direction(lateral length)]>[the length in the vertical direction (longitudinallength)].

Since a pixel array pattern formed by the sub-pixels 32 r, 32 g, and 32b of the plural pixels 32 is defined by a BM pattern 38 of the BM 34surrounding the respective sub-pixels 32 r, 32 g, and 32 b as can beapparently seen from FIG. 4, and the moire occurring when the displayunit 30 and the conductive film 10 or 11 are superimposed on each otheris generated by the interference between the BM pattern 38 of the BM 34of the display unit 30 and the wiring pattern 24 of the conductive film10 or 11, the BM pattern 38 is herein considered to be identical to thepixel array pattern, although it, strictly speaking, is identical to areversed pixel array pattern.

When the conductive film 10 or 11, for example, is disposed on thedisplay panel of the display unit 30 having the BM pattern 38 formed bythe BM 34, the wiring pattern 24 of the conductive film 11 has beenoptimized in terms of visibility of moire with respect to the BM (pixelarray) pattern 38 and then randomized, so that there is no interferencein spatial frequency between the array period of the pixels 32 and thewiring arrangement of the thin metal wires 14 of the conductive film 10or 11, occurrence of moire is suppressed, and thus the wiring pattern isproved excellent in visibility of moire.

The display unit 30 illustrated in FIG. 4 may be configured as a displaypanel such as a liquid crystal panel, a plasma panel, an organic ELpanel, and an inorganic EL panel.

Next, a display device in which the conductive film according to thepresent invention is incorporated will be described below with referenceto FIG. 5. In FIG. 5, a projected capacitive type touch panel in whichthe conductive film 11 according to the second embodiment of the presentinvention is incorporated will be described as a representative exampleof a display device 40, but it is needless to say that the presentinvention is not limited to this example.

As shown in FIG. 5, the display device 40 includes the display unit 30(refer to FIG. 4) that can display a color image and/or a monochromeimage, a touch panel 44 that detects a contact position on an inputsurface 42 (located on the side as directed by arrow Z1), and a housing46 in which the display unit 30 and the touch panel 44 are housed. Theuser can access the touch panel 44 through a large opening provided inone face (on the side as directed by arrow Z1) of the housing 46.

The touch panel 44 includes not only the conductive film 11 (refer toFIG. 3) described above but also a cover member 48 stacked on one face(on the side as directed by arrow Z1) of the conductive film 11, aflexible substrate 52 electrically connected to the conductive film 11through a cable 50, and a detection control unit 54 disposed on theflexible substrate 52.

The conductive film 11 is bonded to one face (on the side directed byarrow Z1) of the display unit 30 through an adhesive layer 56. Theconductive film 11 is disposed on the display screen such that theother, main face side (second conductive portion 16 b side) is oppositeto the display unit 30.

The cover member 48 functions as the input surface 42 by covering oneface of the conductive film 11. In addition, by preventing directcontact with a contact body 58 (for example, a finger or a stylus pen),it suppresses the occurrence of a scratch, adhesion of dust, and thelike, and thus stabilizes the conductivity of the conductive film 11.

The material of the cover member 48 may be glass or a resin film. Oneface (on the side as directed by arrow Z2) of the cover member 48 may becoated with silicon oxide or the like and adhered to one face (on theside as directed by arrow Z1) of the conductive film 11. In order toprevent damage due to rubbing or the like, the conductive film 11 andthe cover member 48 may be formed into a laminate.

The flexible substrate 52 is an electronic substrate having flexibility.In the example shown in this diagram, the flexible substrate 52 is fixedto an inner wall of the housing 46, while the position of the substratemay be varied. The detection control unit 54 constitutes an electroniccircuit that catches a change in the capacitance between the contactbody 58 and the conductive film 11 and detects the contact position (orthe approach position) when the contact body 58 that is a conductor isbrought into contact with (or comes closer to) the input surface 42.

The display device to which the conductive film according to the presentinvention is applied basically has the above-mentioned configuration.

Next, processes of evaluating a wiring pattern of the conductive film onvisibility of moire with respect to a predetermined BM pattern of thedisplay device, performing optimization, and giving irregularity in thepresent invention will be described below. That is, the processes ofdetermining, in the conductive film according to the present invention,a wiring pattern which is optimized so that moire with respect to apredetermined BM pattern of the display device is not perceived by humanvisual sensation, and then given irregularity will be described below.

FIG. 6 is a flowchart illustrating an example of a method of determininga wiring pattern of the conductive film according to the presentinvention.

In the method of determining a wiring pattern of the conductive filmaccording to the present invention, frequencies and intensities of moireare calculated from the peak frequencies and intensities obtained byfrequency analysis using fast Fourier transform (FFT) of the BM (pixelarray) pattern of the display unit of the display device and the wiringpattern of the conductive film, frequencies and intensities of moirebeing not visible are empirically determined from the calculatedfrequencies and intensities of moire, and a wiring pattern satisfyingthese frequency and intensity conditions is determined as a wiringpattern optimized so that moire is not visually recognized. In themethod according to the present invention that generally uses FFT forthe frequencies and intensities of moire, the following processes aredefined because the frequencies/intensities of a target may greatly varydepending on the way of usage.

In the method according to the present invention, first, as Process 1,transmittance image data of the BM pattern and the wiring pattern isprepared. That is, as illustrated in FIG. 6, in step S10, transmittanceimage data of the BM pattern 38 (BM 34) (see FIG. 4) of the display unit30 of the display device 40 illustrated in FIG. 5 and transmittanceimage data of the wiring pattern 62 (of the thin metal wires 14) of theconductive film 60 (see FIG. 7B) are prepared and acquired. When thetransmittance image data of the BM pattern 38 and the transmittanceimage data of the wiring pattern 62 are provided or stored in advance,the data may be acquired from among those provided or stored.

For example, as illustrated in FIG. 7A and FIG. 7C which is apartially-enlarged view of FIG. 7A, the BM pattern 38 of the displayunit 30 can be set to a pattern which comprises the sub-pixels 32 r, 32g and 32 b for three colors R, G and B per pixel 32. When a single coloris used and, for example, only the sub-pixels 32 g of G channel areused, it is preferable that the transmittance image data of R channeland B channel be set to 0. In the present invention, image data of theBM 34, that is, the transmittance image data of the BM pattern 38 is notlimited to the pattern having rectangular openings of the BM 34 (for thesub-pixels 32 r, 32 g, and 32 b) as illustrated in FIG. 7C. A usable BMpattern may not have the rectangular openings of the BM 34 or a BMpattern having arbitrary BM openings may be designated and used. Forexample, the BM pattern is not limited to a pattern having simplerectangular openings, but the BM pattern may have notched rectangularopenings, strip-like openings bent at a predetermined angle, curvedstrip-like openings, or hooked openings.

Meanwhile, the wiring pattern 62 of the conductive film 60 may be in asquare lattice shape as illustrated in FIG. 7B, whereupon the thin metalwires 14 forming the wiring pattern are so arranged as to incline 45degrees.

Here, the size of the transmittance image data of the BM pattern 38 andthe wiring pattern 62 is defined to be, for example, 4096 (pixels)×4096(pixels). In order to prevent or reduce artifacts of period during theFFT processing of Process 2 to be described later, it is preferable thatthe images of the BM pattern 38 and the wiring pattern 62 be eachsubjected to flipping processing in all directions (eight directions) asillustrated in FIG. 8. A new image size after the flipping processing ispreferably the image size (8192 (pixels)=4096 (pixels)×2 for each side)of the area surrounded with a dotted line in FIG. 8 that corresponds tofour images.

Next, as Process 2, the transmittance image data prepared in Process 1is subjected to a two-dimensional fast Fourier transform (2DFFT (base2)). That is, as illustrated in FIG. 6, in step S12, the transmittanceimage data of the BM pattern 38 and the transmittance image data of thewiring pattern 62 prepared in step S10 are each subjected to the 2DFFT(base 2) processing, and peak frequencies and peak intensities of pluralspectrum peaks in each of the two-dimensional Fourier spectrums of thetransmittance image data of the BM pattern 38 and the wiring pattern 62are calculated. Here, the peak intensities are treated as their absolutevalues.

FIGS. 9A and 9B are diagrams illustrating intensity characteristics ofthe two-dimensional Fourier spectrums of the transmittance image data ofthe BM pattern 38 and the wiring pattern 62, respectively.

In FIGS. 9A and 9B, the intensity is high in white parts, that is tosay, the white parts indicate spectrum peaks. Accordingly, the peakfrequencies and the peak intensities of the spectrum peaks arecalculated for each of the BM pattern 38 and the wiring pattern 62 fromthe results illustrated in FIGS. 9A and 9B. In other words, with respectto the spectrum peaks found in the intensity characteristics of thetwo-dimensional Fourier spectrums of the BM pattern 38 and the wiringpattern 62 as illustrated in FIGS. 9A and 9B, respectively, positions ofthe spectrum peaks, namely peak positions, on the frequency coordinatesrepresent peak frequencies, and intensities of the two-dimensionalFourier spectrums at the peak positions are peak intensities.

Here, the peak frequencies and the peak intensities of the spectrumpeaks of the BM pattern 38 and the wiring pattern 62 are calculated andacquired as follows.

First, in calculation of peaks for acquiring the peak frequencies,frequency peaks are calculated from the basic frequencies of the BMpattern 38 and the wiring pattern 62. This is because the transmittanceimage data to be subjected to the 2DFFT processing is acquired asdiscrete values and thus the peak frequency depends on the reciprocal ofthe image size. As illustrated in FIG. 10, frequency peak positions canbe expressed by a combination of independent two-dimensional basicfrequency vector components a(bar) and b(bar). Consequently, theacquired peak positions form a lattice shape. While FIG. 10 is a graphillustrating the frequency peak positions in the case of the BM pattern38, the frequency peak positions for the wiring pattern 62 can becalculated in the same way.

Meanwhile, in acquiring of peak intensities, since the peak positionsare calculated in the aforementioned acquisition of the peakfrequencies, the intensities (absolute values thereof) of thetwo-dimensional Fourier spectrums at the peak positions are acquired. Atthis time, since digital data is subjected to the FFT processing, a peakposition may be located on plural pixels at a time. For example, whenthe intensity (Sp) characteristics of a two-dimensional Fourier spectrumare expressed by the curve (analog values) illustrated in FIG. 11A, thedigitized intensity characteristics of the same two-dimensional Fourierspectrum are expressed by the bar graph (digital values) illustrated inFIG. 11B, and the intensity peak P of the two-dimensional Fourierspectrum illustrated in FIG. 11A is on the boundary between two pixelsin FIG. 11B corresponding to FIG. 11A. Accordingly, at the time ofacquiring the intensity present at a peak position, the average ofspectral intensities of some pixels selected in descending order ofspectral intensity from an area including plural pixels around the peakposition, for example, five pixels selected in descending order ofspectral intensity from an area of 5×5 pixels, is preferably set as thepeak intensity (absolute value).

Here, it is preferable that the acquired peak intensity be normalizedwith the image size. In the above-mentioned example, it is preferablethat the peak intensity be normalized with an image size of 8192×8192(Parseval's theorem).

Then, as Process 3, frequency information and intensity information ofmoire are calculated. That is, as illustrated in FIG. 6, in step S14,the frequency information and the intensity information of moire arerespectively calculated from the peak frequencies and the peakintensities of the two-dimensional Fourier spectrums of the BM pattern38 and the wiring pattern 62 calculated in step S12. Here, the peakintensities and the intensity information of moire are also treated astheir absolute values.

Since moire is essentially caused by the multiplication of thetransmittance image data of the wiring pattern 62 and the BM pattern 38in the real space, a convolution of the two patterns is to be performedin the frequency space. However, since the peak frequencies and the peakintensities of the two-dimensional Fourier spectrums of the BM pattern38 and the wiring pattern 62 are calculated in step S12, the difference(absolute value of the difference) between the frequency peaks of thetwo patterns may be calculated so as to determine the calculateddifference to be the frequency information of moire, and the product oftwo combinations of vector intensities of the patterns may be calculatedso as to determine the calculated product to be the intensityinformation (absolute value) of moire.

Here, the difference between the frequency peaks found in the intensitycharacteristics of the two-dimensional Fourier spectrums of the BMpattern 38 and the wiring pattern 62 respectively illustrated in FIGS.9A and 9B corresponds to the relative distance between the peakpositions on the frequency coordinates of the frequency peaks of the twopatterns that are found in the intensity characteristics acquired bysuperimposing the intensity characteristics of the two-dimensionalFourier spectrums of the patterns on each other.

Since the number of spectrum peaks in the two-dimensional Fourierspectrums of the BM pattern 38 and the wiring pattern 62 is two or morefor each spectrum, differences between the frequency peaks as values ofthe relative distance are also two or more in number, that is to say,the frequency information of moire is obtained as two or more pieces ofinformation. Accordingly, when a large number of spectrum peaks arepresent in the two-dimensional Fourier spectrums, the number of piecesof frequency information of moire to be calculated also becomes large,and the time is required for the calculation thereof. In that case, onlyspectrum peaks with high peak intensities may be selected in advancefrom among the spectrum peaks in the respective two-dimensional Fourierspectrums. Since only the differences between the peaks respectivelyselected are calculated, the calculation time can be shortened.

The frequency information of moire and the intensity information ofmoire acquired in this way are illustrated in FIG. 12. FIG. 12 is adiagram schematically illustrating the frequency information and theintensity information of the moire generated by interference between thepixel array pattern illustrated in FIG. 7A and the wiring patternillustrated in FIG. 7B, and it can be said that FIG. 12 illustrates theresult of the convolution between the intensity characteristics of thetwo-dimensional Fourier spectrums illustrated in FIGS. 9A and 9B.

In FIG. 12, the frequency information of moire is expressed by positionson the vertical and horizontal axes and the intensity information ofmoire is expressed by a gray scale (achromatic colors), where a darkercolor indicates a lower intensity and a lighter color, namely, a colorcloser to white indicates a higher intensity.

Then, as Process 4, a visibility limit value of moire is determined.

Specifically, first, as illustrated in FIG. 6, in step S16, a standardvisual response characteristic of human beings illustrated in FIG. 13 isapplied to the frequency information of moire and the intensityinformation (absolute value thereof) of moire acquired in step S14, thatis to say, the acquired frequency information and intensity informationof moire are multiplied by the standard visual response characteristic,and the frequency of moire and the intensity (absolute value) of moireare calculated. In other words, the acquired frequency information andintensity information of moire are convoluted with a visual transferfunction (VTF) illustrated in FIG. 13 as an exemplary standard visualresponse characteristic of human beings. The visual transfer functionhas a Dooley-Shaw function as a basis and removes attenuation ofsensitivity to low-frequency components.

In this embodiment, the Dooley-Shaw function at an observation distanceof 300 mm under conditions of distinct vision is used as a standardvisual response characteristic of human beings. The Dooley-Shaw functionis a kind of visual transfer function (VTF) and is a representativefunction simulating a standard visual response characteristic of humanbeings. Specifically, the Dooley-Shaw function corresponds to the squareof the contrast ratio characteristic of luminance. The horizontal axisof the graph represents the spatial frequency (unit: cycles/mm) and thevertical axis represents the VTF value (unit: dimensionless).

When the observation distance is 300 mm, the VTF value is constant(equal to 1) in a range of 0 cycle/mm to 1.0 cycles/mm and the VTF valuetends to decrease as the spatial frequency increases. That is, thisfunction serves as a low-pass filter that cuts off mid-to-high spatialfrequency bands.

The actual visual response characteristic of human beings has a valuesmaller than 1 in the vicinity of 0 cycle/mm and thus shows a so-calledband-pass filter characteristic. However, in this embodiment, theattenuation of sensitivity to low-frequency components is removed bysetting the VTF value to 1 even in a very low spatial frequency band, asillustrated in FIG. 13. Accordingly, it is possible to suppressperiodicity due to the repeated arrangement of the wiring pattern 62.

Then, as illustrated in FIG. 6, in step S18, with respect to thefrequencies of moire and the intensities (absolute values thereof) ofmoire acquired in step S16, the sum of the intensities (absolute valuesthereof) of moire which are each corresponding to a frequency of moirefalling within a predetermined frequency range determined depending onthe standard visual response characteristic is calculated. That is, theconvolution with the VTF is performed and then, with respect to thefrequencies and intensities of moire, ranking for optimization isperformed. Here, for the matching with the visual sensitivity, after theconvolution with the VTF (step S16), conversion to the density isperformed and the common logarithm is applied to the intensities.Further, in order to efficiently perform ranking in visibility of moire,the following conditions are empirically set up. That is, in theconditions below, the intensity of moire refers to the density asconverted therefrom.

The conditions for the above ranking of patterns are as follows.

1. The ranking should be performed using only data in which the spatialfrequency of moire is up to 3 cycles/mm.

2. A pattern involving an intensity of moire greater than or equal to −5at a spatial frequency of 1.8 cycles/mm or less should not undergo theranking.

3. A pattern involving an intensity of moire greater than or equal to−3.7 at a spatial frequency greater than 1.8 cycles/mm but not greaterthan 3 cycles/mm should not undergo the ranking.

Under these conditions, a smaller sum of the intensities of moire ismore preferable, and the wiring pattern 62 which causes the sum of theintensities of moire to be less than or equal to 0 in terms of commonlogarithm (less than or equal to 1 in terms of antilogarithm) is set asthe optimized wiring pattern 24 of the present invention. When pluraloptimized wiring patterns 24 are acquired, needless to say, the wiringpattern causing the smallest sum of the intensities of moire is set asthe best wiring pattern 24, and the plural optimized wiring patterns 24are ranked.

With respect to a large number of wiring patterns 62, the sum of theintensities of moire was calculated using simulation samples and actualsamples, and three researchers evaluated the wiring patterns 62 and thesums of the intensities of moire. When the sum of the intensities ofmoire was less than or equal to −4 in terms of common logarithm (lessthan or equal to 10⁻⁴ in terms of antilogarithm), moire was not visuallyrecognized at all through sensory evaluation, which was evaluated to beexcellent (++). When the sum of the intensities of moire was greaterthan −4 but not greater than −2.5 in terms of common logarithm (greaterthan 10⁻⁴ but not greater than 10^(−2.5) in terms of antilogarithm),moire was hard to visually recognize through sensory evaluation, whichwas evaluated to be good (+). When the sum of the intensities of moirewas greater than −2.5 but not greater than 0 in terms of commonlogarithm (greater than 10^(−2.5) but not greater than 1 in terms ofantilogarithm), moire was visually recognized through sensory evaluationbut to a slight and negligible extent, which was evaluated to be fair(+−). When the sum of the intensities of moire was greater than 0 interms of common logarithm (greater than 1 in terms of antilogarithm),moire was visually recognized through sensory evaluation, which wasevaluated to be no good (unacceptable).

Therefore, in the present invention, the sum of the intensities of moireis limited to be less than or equal to 0 in terms of common logarithm(less than or equal to 1 in terms of antilogarithm).

Then, as illustrated in FIG. 6, in step S20, the sum of the intensitiesof moire calculated in step S18 is compared with a predetermined valueso as to determine whether it is true or not that the sum of theintensities of moire is less than or equal to the predetermined value,for example, 0.

When it is determined as a result of comparison that the sum of theintensities of moire is greater than the predetermined value, thetransmittance image data of the wiring pattern 62 is renewed totransmittance image data of another wiring pattern in step S22, and theroutine is returned to step S12.

Here, the wiring pattern for data renewal may be provided in advance ormay be prepared newly. When the wiring pattern is newly prepared, one ormore of the rotation angle, the pitch and the pattern width in thetransmittance image data of the wiring pattern may be changed, or theshape or the size of the openings of the wiring pattern may be changed.In addition, randomness may be given to such factors.

Thereafter, the calculation of the peak frequencies and the peakintensities in step S12, the calculation of the frequency informationand intensity information of moire in step S14, the calculation of thefrequency and intensity of moire in step S16, the calculation of the sumof the intensities of moire in step S18, the comparison of the sum ofthe intensities of moire with the predetermined value in step S20, andthe renewal of the transmittance image data of the wiring pattern instep S22 are repeatedly performed until the sum of the intensities ofmoire is less than or equal to the predetermined value.

On the other hand, when it is determined that the sum of the intensitiesof moire is less than or equal to the predetermined value, the wiringpattern 62 is set in step S24 as an optimized rhomboidal wiring pattern64 illustrated in FIG. 14.

Then, as illustrated in FIG. 6, in step S26, irregularity in apredetermined range determined depending on the width of the thin metalwires 14 is given to a rhomboid shape of the optimized rhomboidal wiringpattern 64 as specified in step S24, and the resultant wiring pattern isdetermined to be the wiring pattern 24 of the conductive film 10 or 11according to the present invention.

Here, the giving of predetermined irregularity in step S26 can beperformed as follows.

First, to the rhomboid shape of the optimized wiring pattern 64illustrated in FIG. 14, predetermined irregularity is given by movingone line constituting rhomboid by a predetermined distance in parallelalong a direction parallel to a side of rhomboid, that is, the directionof arrow A in the drawing, or a direction perpendicular to a side ofrhomboid, that is, the direction of arrow B in the drawing.

In the present invention, when one line constituting rhomboid is movedin the direction A parallel to a side of rhomboid, the direction inwhich irregularity is given is referred to as the direction A parallelto a side of rhomboid, and in this case, the pitch of rhomboid ispreserved before and after the irregularity is given. Accordingly, sincethe pitch of rhomboid is preserved and the angle is randomly changed, apattern given irregularity as such can be considered as thepitch-preserved and angle-randomized pattern whose rhomboid shape israndomly changed while kept parallelogrammatic.

On the other hand, when one line constituting rhomboid is moved in thedirection B perpendicular to a side of rhomboid, the direction in whichirregularity is given is referred to as the direction B perpendicular toa side of rhomboid, and in this case, the angle θ of rhomboid ispreserved before and after the irregularity is given. Accordingly, sincethe pitch of rhomboid is randomly changed and the angle is preserved, apattern given irregularity as such can be considered as thepitch-randomized and angle-preserved pattern in which the pitch ofrhomboid is randomly changed while the angle is kept constant.

In the present invention, when the direction in which the irregularityis given to the rhomboid shape of the optimized rhomboidal wiringpattern 64 is the direction A parallel to a side of rhomboid or thedirection B perpendicular to a side of rhomboid, the irregularity isdefined as a ratio of the average according to a normal distribution forthe pitch of rhomboid after the irregularity is given with respect tothe pitch of rhomboid before the irregularity is given.

In the present invention, it is preferable that the irregularity definedas above is limited to a predetermined range of 2% to 20% when the widthof the thin metal wires is less than or equal to 3 μm, and to a range of2% to 10% when the width of the thin metal wires is greater than 3 μm.In the case of the above-mentioned pitch-randomized pattern, it is morepreferable that the irregularity is limited to a predetermined range of2% to 10% when the width of the thin metal wires is less than or equalto 3 μm, and to a range of 2% to 8% when the width of the thin metalwires is greater than 3 μm.

The reason for limiting the irregularity to such a range is as follows:If the irregularity falls within the range, the occurrence of moire isfurther suppressed and the wiring pattern is made more excellent invisibility of moire, that is to say, the occurrence of moire issuppressed and the wiring pattern is kept excellent in visibility ofmoire even if the BM pattern on which the wiring pattern is superimposedis somewhat varied. In contrast, the above effects cannot be achieved bythe giving of irregularity without the range.

The giving of predetermined irregularity in step S26 can be performed asdescribed above.

In this way, the method for determining the wiring pattern of theconductive film according to the present invention is finished and thewiring pattern 24 of the conductive film 10 or 11 according to thepresent invention can be determined.

As a result, it is possible to manufacture the conductive film accordingto the present invention having the wiring pattern as optimized and thengiven irregularity that can be superimposed on a BM pattern of a displayunit of a display device with no moire occurring and is thus excellentin visibility of moire.

In the present invention, since the irregularity within thepredetermined range as above is further given to the wiring patternwhich has been optimized with respect to a predetermined BM pattern, theoccurrence of moire is further suppressed and the wiring pattern is mademore excellent in visibility of moire, that is to say, the occurrence ofmoire is suppressed and the wiring pattern is kept excellent invisibility of moire even if the BM pattern on which the wiring patternis superimposed is somewhat varied.

While the conductive film according to the present invention, thedisplay device equipped with the conductive film, and the method fordetermining a pattern of the conductive film have been described abovewith reference to various embodiments and examples, the presentinvention is not limited to the embodiments and examples but, as amatter of course, may be improved or modified in various forms withoutdeparting from the gist of the present invention.

EXAMPLES

Hereinafter, the present invention will be described in more detail withreference to examples of the present invention.

A wiring pattern 24 was prepared by giving irregularity to the optimizedrhomboidal wiring pattern 64 illustrated in FIG. 14, and the resultantwiring pattern was superimposed on the BM pattern 38 illustrated in FIG.7A so as to conduct sensory evaluation about the visibility of moire.

In the optimized rhomboidal wiring patterns 64 illustrated in FIG. 14,the angle of rhomboid is 30° and the pitch of rhomboid is 200 μm. Thethin metal wires 14 as used were two in type of line width, those with aline width of 2 μm and those with a line width of 4 μm.

A black matrix (168 v8 h32) having the BM pattern 38 illustrated in FIG.7A was used as the BM 34.

First, as Example 1, two types of wiring patterns, namely, apitch-preserved wiring pattern (pitch preserved) in which the width ofthe thin metal wires 14 was 4 the angle of rhomboid was 30°, the pitchof rhomboid was 200 μm, the irregularity illustrated in FIG. 15A was 2%,and the irregularity direction was the direction A, and apitch-randomized wiring pattern (angle preserved) in which the width ofthe thin metal wires 14, the angle of rhomboid and the pitch of rhomboidwere the same as those in the aforementioned pitch-preserved wiringpattern, the irregularity illustrated in FIG. 16A was 2%, and theirregularity direction was the direction B were manufactured and wererespectively bonded to the display screen of the display unit 30 havingthe BM 34. A commercially-available liquid crystal display (resolution:about 150 dpi, 10.1-inch, 1280×800) and four types of displays havingidentical specifications were used as the display unit 30 forconfirmation. In a state where the display unit 30 was so controlled asto display in white (at the highest luminance), three researchersrespectively performed sensory evaluation with regard to the visibilityof moire. The observation distance from the display screen was set to300 mm and the indoor illuminance was set to 300 lx.

Evaluation about Moire

The case where moire was not visualized was rated “A”, the case wheremoire was visually recognized but at a level with no problem was rated“B”, and the case where moire was visualized was rated “C”. The averageof the ratings by the researchers was regarded as a moire evaluationresult.

The results are shown in Table 1.

Subsequently, as Examples 2 to 5 and Comparative Examples 1 and 2, twotypes of wiring patterns were manufactured in the same way as in Example1, except that the irregularity was replaced with 4%, 6%, 8%, 10%, 20%or 40%. The pitch-preserved wiring pattern of Example 2 in which theirregularity was 4% and the irregularity direction was the direction Aand the pitch-randomized wiring pattern of Example 2 in which theirregularity was 4% and the irregularity direction was the direction Bare illustrated in FIGS. 15B and 16B, respectively. In addition, thepitch-preserved wiring pattern of Comparative Example 2 in which theirregularity was 40% and the irregularity direction was the direction Aand the pitch-randomized wiring pattern of Comparative Example 2 inwhich the irregularity was 40% and the irregularity direction was thedirection B are illustrated in FIGS. 15C and 16C, respectively.

The two types of wiring patterns as manufactured in this way wererespectively bonded to the display screen of the display unit 30 so asto conduct sensory evaluation about moire.

The results are shown in Table 1.

TABLE 1 line width 4 [μm] angle 30 [deg] pitch 200 [μm] Example 1Example 2 Example 3 Example 4 Example 5 Com. Ex. 1 Com. Ex. 2Irregularity 2% 4% 6% 8% 10% 20% 40% Angle-preserved A A A A B C C(direction B) Pitch-preserved A A A A A C C (direction A)

Further, as Example 11, two types of wiring patterns were manufacturedin the same way as in Example 1, except that the line width was changedto 2 μm. Moreover, as Examples 12 to 16 and Comparative Example 11, twotypes of wiring patterns were manufactured in the same way as in Example1, except that the line width was changed to 2 μm and the irregularitywas replaced with 4%, 6%, 8%, 10%, 20% or 40%. The manufactured wiringpatterns were bonded to the display screen of the display unit 30 so asto conduct sensory evaluation about moire.

The results are shown in Table 2.

TABLE 2 line width 2 [μm] angle 30[deg] pitch 200 [μm] Example 11Example 12 Example 13 Example 14 Example 15 Example 16 Com. Ex. 11Irregularity 2% 4% 6% 8% 10% 20% 40% Angle-preserved A A A A A B C(direction B) Pitch-preserved A A A A A A C (direction A)

As evidently seen from Table 1 and Table 2, in Examples 1 to 5 as givenirregularity within its limitation range determined according to a linewidth of 4 μm and Examples 11 to 16 as given irregularity within itslimitation range determined according to a line width of 2 μm, moire wasnot visualized or moire was visually recognized but at a level with noproblem. In other words, the above Examples were proved excellent invisibility of moire as compared with Comparative Examples 1, 2 and 11 inwhich moire was visualized.

The advantageous effects of the present invention can be understood fromthe above description.

What is claimed is:
 1. A conductive film adapted to be installed on adisplay unit of a display device, comprising: a transparent substrate;and a conductive portion including a plurality of thin metal wires thatis formed on at least one surface of the transparent substrate, whereinthe conductive portion has a wiring pattern obtained by givingirregularity to a rhomboidal wiring pattern, said wiring pattern beingformed by the plurality of thin metal wires in a meshed manner andarraying a plurality of openings, wherein the wiring pattern issuperimposed on a pixel array pattern of the display unit, and whereinthe wiring pattern is a randomized wiring pattern having randomizedrhomboid shapes obtained by giving the irregularity in a predeterminedrange determined depending on a line width of the thin metal wires torhomboid shapes of the rhomboidal wiring pattern which, with respect tofrequencies of moire and intensities of moire obtained by applying avisual response characteristic of human beings to frequency informationof moire and intensity information of moire calculated from peakfrequencies and peak intensities of plural spectrum peaks in atwo-dimensional Fourier spectrum of transmittance image data of therhomboidal wiring pattern and peak frequencies and peak intensities ofplural spectrum peaks in a two-dimensional Fourier spectrum oftransmittance image data of the pixel array pattern, causes a sum ofintensities of moire each corresponding to each of frequencies of moirefalling within a predetermined frequency range determined depending onthe visual response characteristic to be less than or equal to apredetermined value, wherein, when a direction in which the irregularityis given to the rhomboid shape is a direction parallel or perpendicularto a side of rhomboid, the irregularity is defined as a ratio of anaverage according to a normal distribution for a pitch of rhomboid afterthe irregularity is given with respect to the pitch of rhomboid beforethe irregularity is given, and wherein the predetermined range of theirregularity is from 2% to 20% when the line width of the thin metalwires is less than or equal to 3 μm and the predetermined range of theirregularity is from 2% to 10% when the line width of the thin metalwires is greater than 3 μm, wherein the frequency of moire and theintensity of moire are obtained by performing convolution with a visualtransfer function as the visual response characteristic on the frequencyinformation of moire and the intensity information of moire.
 2. Theconductive film according to claim 1, wherein the pitch of rhomboid ispreserved before and after the irregularity is given when the directionin which the irregularity is given to the rhomboid shape is thedirection parallel to a side of rhomboid, and wherein an angle ofrhomboid is preserved before and after the irregularity is given whenthe direction in which the irregularity is given to the rhomboid shapeis the direction perpendicular to a side of rhomboid.
 3. The conductivefilm according to claim 1, wherein the predetermined frequency range ofthe frequency of moire is up to 3 cycles/mm, and wherein the wiringpattern undergoes ranking for optimization in a case in which itinvolves a frequency of moire less than or equal to 3 cycles/mm, and thewiring pattern undergoing the ranking for optimization causes the sum ofintensities of moire to be less than or equal to 0 in terms of commonlogarithm on condition that the wiring pattern does not undergo theranking for optimization in a case in which it involves an intensity ofmoire greater than or equal to −5 in terms of common logarithm at afrequency of moire less than or equal to 1.8 cycles/mm and in a case inwhich it involves an intensity of moire greater than or equal to −3.7 interms of common logarithm at a frequency of moire greater than 1.8cycles/mm but not greater than 3 cycles/mm.
 4. The conductive filmaccording to claim 1, wherein the frequency information of moire isgiven as differences between the peak frequencies of the wiring patternand the peak frequencies of the pixel array pattern and the intensityinformation of moire is given as products of the peak intensities of thewiring pattern and the peak intensities of the pixel array pattern. 5.The conductive film according to claim 1, wherein the peak intensitiesare each an average of intensities in a plurality of pixels around apeak position.
 6. The conductive film according to claim 1, wherein thepeak intensities are normalized with the transmittance image data of thewiring pattern and the pixel array pattern.
 7. The conductive filmaccording to claim 1, wherein the pixel array pattern is a black matrixpattern.
 8. A display device, comprising: a display unit; and theconductive film according to claim 1 that is installed on the displayunit.
 9. The conductive film according to claim 1, wherein the visualtransfer function has a Dooley-Shaw function as a basis and removesattenuation of sensitivity to low-frequency components.
 10. A method fordetermining a wiring pattern of a conductive film, with the conductivefilm being adapted to be installed on a display unit of a display deviceand to have a wiring pattern obtained by giving irregularity to arhomboidal wiring pattern, said wiring pattern being formed by theplurality of thin metal wires in a meshed manner and arraying aplurality of openings, comprising the steps of: acquiring transmittanceimage data of a predetermined wiring pattern and transmittance imagedata of a pixel array pattern of the display unit, on which pattern thepredetermined wiring pattern is superimposed; calculating peakfrequencies and peak intensities of plural spectrum peaks in atwo-dimensional Fourier spectrum of the transmittance image data of thepredetermined wiring pattern and peak frequencies and peak intensitiesof plural spectrum peaks in a two-dimensional Fourier spectrum of thetransmittance image data of the pixel array pattern by performing atwo-dimensional Fourier transform on the transmittance image data of thepredetermined wiring pattern and the transmittance image data of thepixel array pattern; calculating frequency information of moire andintensity information of moire from the peak frequencies and the peakintensities of the predetermined wiring pattern and the pixel arraypattern thus calculated, respectively; calculating frequencies of moireand intensities of moire by applying a visual response characteristic ofhuman beings to the frequency information of moire and the intensityinformation of moire thus obtained; making comparison with respect tothe frequencies of moire and the intensities of moire thus obtained suchthat a sum of intensities of moire each corresponding to each offrequencies of moire falling within a predetermined frequency rangedetermined depending on the visual response characteristic is comparedwith a predetermined value; changing the transmittance image data of thepredetermined wiring pattern to transmittance image data of a new wiringpattern in a case in which the sum of the intensities of moire isgreater than the predetermined value, and repeating the steps ofcalculating the peak frequencies and the peak intensities, calculatingthe frequency information of moire and the intensity information ofmoire, calculating the frequencies of moire and the intensities ofmoire, and making comparison between the sum of the intensities of moireand the predetermined value until the sum of the intensities of moire isless than or equal to the predetermined value; setting a rhomboidalwiring pattern which causes the sum of the intensities of moire to beless than or equal to the predetermined value as the wiring pattern ofthe conductive film; and giving the irregularity in a predeterminedrange determined depending on a width of the thin metal wires torhomboid shapes of the set rhomboidal wiring pattern, and determining arandomized wiring pattern having randomized rhomboid shapes that theirregularity is given to be the wiring pattern of the conductive film,wherein the frequency of moire and the intensity of moire are obtainedby performing convolution with a visual transfer function as the visualresponse characteristic on the frequency information of moire and theintensity information of moire, wherein the predetermined frequencyrange of the frequency of moire is up to 3 cycles/mm, and wherein thepredetermined wiring pattern undergoes ranking for optimization in acase in which it involves a frequency of moire less than or equal to 3cycles/mm, and the predetermined wiring pattern undergoing the rankingfor optimization causes the sum of intensities of moire to be less thanor equal to 0 in terms of common logarithm on condition that thepredetermined wiring pattern does not undergo the ranking foroptimization in a case in which it involves an intensity of moiregreater than or equal to −5 in terms of common logarithm at a frequencyof moire less than or equal to 1.8 cycles/mm and in a case in which itinvolves an intensity of moire greater than or equal to −3.7 in terms ofcommon logarithm at a frequency of moire greater than 1.8 cycles/mm butnot greater than 3 cycles/mm.
 11. The method for determining a wiringpattern of a conductive film according to claim 10, wherein, when adirection in which the irregularity is given to the rhomboid shape is adirection parallel or perpendicular to a side of rhomboid, theirregularity is defined as a ratio of an average according to a normaldistribution for a pitch of rhomboid after the irregularity is givenwith respect to the pitch of rhomboid before the irregularity is given,and wherein the predetermined range of the irregularity is from 2% to20% when the width of the thin metal wires is less than or equal to 3 μmand the predetermined range of the irregularity is from 2% to 10% whenthe width of the thin metal wires is greater than 3 μm.
 12. The methodfor determining a wiring pattern of a conductive film according to claim10, wherein the pitch of rhomboid is preserved before and after theirregularity is given when the direction in which the irregularity isgiven to the rhomboid shape is the direction parallel to a side ofrhomboid, and wherein an angle of rhomboid is preserved before and afterthe irregularity is given when the direction in which the irregularityis given to the rhomboid shape is the direction perpendicular to a sideof rhomboid.
 13. The method for determining a wiring pattern of aconductive film according to claim 10, wherein the frequency informationof moire is obtained as differences between the peak frequencies of thepredetermined wiring pattern and the peak frequencies of the pixel arraypattern, and wherein the intensity information of moire is obtained asproducts of two sets of vector intensities, with one set comprising thepeak intensities of the predetermined wiring pattern and the othercomprising the peak intensities of the pixel array pattern.
 14. Themethod for determining a wiring pattern of a conductive film accordingto claim 10, wherein the visual transfer function has a Dooley-Shawfunction as a basis and removes attenuation of sensitivity tolow-frequency components.